Magnetic heads used in disk drives typically incorporate air bearing sliders carrying magnetic transducers that fly over the surface of a magnetic disk for reading and writing data on the disk. The slider is supported by a gimbal connected to a load beam of a head arm suspension assembly. In response to signals from a control unit or computer, the suspension assembly positions the slider over selected tracks of the disk. As the disk rotates it generates an air flow parallel to the tangential velocity of the disk. The air flow provides a lift that allows the slider to fly above the disk. A close spacing or flying height between the transducer and the disk improves the transducing relationship between the magnetic transducer and the magnetic disk. When used with very narrow transducing gaps and very thin magnetic record films, the close spacing allows short wavelength, high frequency signals to be recorded, thereby affording high density, high storage capacity recording.
A major thrust in disk drive design is toward smaller compact drives with smaller components. As a result, head suspensions and head sliders are being reduced in size. The next generation of magnetic disk drives have pico-size sliders, and a planar head air bearing design where usable slider surface area is reduced substantially. A pico-size slider is about 0.049 inches long, about 0.039 inch wide and about 0.012 inch high. A pico-size slider is about 30% of the size of a standard slider. A micro-slider is about 70% of the size of a standard slider and a nano-slider is about 50% of the size of a standard slider.
Hard drives require minimal change in slider flying height over a range of velocity and skew conditions. This requirement is more difficult to satisfy as the load on the air bearing increases, or as the surface area for the air bearing decreases. In high load applications, e.g. where non-operating shock issues are of concern, maintaining a proper flying-height profile for gram loads that are typical of larger nano-size sliders is desirable.
Current designs for pico-size sliders support loads in the 2.0 to 2.5 gram range, and are able to maintain near constant flying heights from the inside diameter to the outside diameter of a disk in a hard drive. However, when the gram load is pushed up to 3.5 grams, the modeled profile delta (pd) increases to 0.2 or 0.3 micro-inches. Profile deltas above 0.1 micro-inches are considered unacceptable. A "profile delta" is the maximum flying height minus the minimum flying height as the slider tracks from the inside radius of the disk to the outside radius of the disk.
An object of the invention is to provide an air bearing design for a reduced size form factor slider that makes the flight attitude of the slider less sensitive to changes in velocity and skew angle.
Another object of this invention is to provide an air bearing surface for a pico-sized slider which flies at near constant height under conditions of changing velocity and skew angle, at relatively high gram loads.
Another object of this invention is to provide an air bearing slider having constant flying height at different radii of a magnetic storage disk.